5.1.1.1. ASCII2NC: Using Python Embedding with MET_PYTHON_EXE

met_tool_wrapper/ASCII2NC/ASCII2NC_python_embedding _user_py.conf

Scientific Objective

Simply converting file formats so point observations can be read by the MET tools through the use of a user-defined Python script and running in either a different environment that the MET build or using a package not currently a METplus dependency.

Datasets

Observations: Precipitation accumulation observations in ASCII text files

Location: All of the input data required for this use case can be found in the met_test sample data tarball. Click here to the METplus releases page and download smaple data fore the appropriate release: https://github.com/dtcenter/METplus/releases

This tarball should be unpacked into the directory that you will set the value of INPUT_BASE. See Running METplus section for more information.

Data Source: Unknown

METplus Components

This use case utilizes the METplus ASCII2NC wrapper to generate a command to run the MET tool ASCII2NC.

METplus Workflow

ASCII2NC is the only tool called in this example. It has one run time, but the time is not relevant because the files processed do not have any time information in the names.

METplus Configuration

METplus first loads all of the configuration files found in parm/metplus_config, then it loads any configuration files passed to METplus via the command line with the -c option, i.e. -c parm/use_cases/met_tool_wrapper/ASCII2NC/ASCII2NC_python_embedding_user_py.conf

[config]
## Configuration-related settings such as the process list, begin and end times, etc.

# List of applications to run - only ASCII2NC for this case
PROCESS_LIST = ASCII2NC

# time looping - options are INIT, VALID, RETRO, and REALTIME
# If set to INIT or RETRO:
#   INIT_TIME_FMT, INIT_BEG, INIT_END, and INIT_INCREMENT must also be set
# If set to VALID or REALTIME:
#   VALID_TIME_FMT, VALID_BEG, VALID_END, and VALID_INCREMENT must also be set
LOOP_BY = VALID

# Format of VALID_BEG and VALID_END using % items
# %Y = 4 digit year, %m = 2 digit month, %d = 2 digit day, etc.
# see www.strftime.org for more information
# %Y%m%d%H expands to YYYYMMDDHH
VALID_TIME_FMT = %Y%m%d%H

# Start time for METplus run - must match VALID_TIME_FMT
VALID_BEG = 2010010112

# End time for METplus run - must match VALID_TIME_FMT
VALID_END = 2010010112

# Increment between METplus runs (in seconds if no units are specified)
#  Must be >= 60 seconds
VALID_INCREMENT = 1M

# List of forecast leads to process for each run time (init or valid)
# If unset, defaults to 0 (don't loop through forecast leads
LEAD_SEQ = 0

# Order of loops to process data - Options are times, processes
# Not relevant if only one item is in the PROCESS_LIST
# times = run all wrappers in the PROCESS_LIST for a single run time, then
#   increment the run time and run all wrappers again until all times have
#   been evaluated.
# processes = run the first wrapper in the PROCESS_LIST for all times
#   specified, then repeat for the next item in the PROCESS_LIST until all
#   wrappers have been run
LOOP_ORDER = times

# Verbosity of MET output - overrides LOG_VERBOSITY for ASCII2NC only
#LOG_ASCII2NC_VERBOSITY = 1

# MET Configuration file for ASCII2NC
# References CONFIG_DIR from the [dir] section
ASCII2NC_CONFIG_FILE =

# If set to True, skip run if the output file determined by the output directory and
# filename template already exists
ASCII2NC_SKIP_IF_OUTPUT_EXISTS = False

# Time relative to valid time (in seconds if no units are specified) to allow files to be considered
#  valid. Set both BEGIN and END to 0 to require the exact time in the filename
#  Not used in this example.
ASCII2NC_FILE_WINDOW_BEGIN = 0
ASCII2NC_FILE_WINDOW_END = 0

# Time relative to each input file's valid time (in seconds if no units are specified) for data within the file to be
# considered valid.
ASCII2NC_WINDOW_BEGIN = 0
ASCII2NC_WINDOW_END = 0

# Value to pass with the -format argument to ascii2nc. See MET User's Guide for more information
ASCII2NC_INPUT_FORMAT = python

# Value to pass with the -mask_grid argument to ascii2nc. See MET User's Guide for more information
ASCII2NC_MASK_GRID =

# Value to pass with the -mask_poly argument to ascii2nc. See MET User's Guide for more information
ASCII2NC_MASK_POLY =

# Value to pass with the -mask_sid argument to ascii2nc. See MET User's Guide for more information
ASCII2NC_MASK_SID =

# For defining the time periods for summarization
# False for no time summary, True otherwise
# The rest of the ASCII2NC_TIME_SUMMARY variables are ignored if set to False
# See the MET User's Guide section regarding ASCII2NC time summary options for more information.
ASCII2NC_TIME_SUMMARY_FLAG = False
ASCII2NC_TIME_SUMMARY_RAW_DATA = False
ASCII2NC_TIME_SUMMARY_BEG = 000000
ASCII2NC_TIME_SUMMARY_END = 235959
ASCII2NC_TIME_SUMMARY_STEP = 300
ASCII2NC_TIME_SUMMARY_WIDTH = 600
ASCII2NC_TIME_SUMMARY_GRIB_CODES = 11, 204, 211
ASCII2NC_TIME_SUMMARY_VAR_NAMES =
ASCII2NC_TIME_SUMMARY_TYPES = min, max, range, mean, stdev, median, p80
ASCII2NC_TIME_SUMMARY_VALID_FREQ = 0
ASCII2NC_TIME_SUMMARY_VALID_THRESH = 0.0


# End of [config] section and start of [dir] section
[dir]
# location of configuration files used by MET applications
CONFIG_DIR={PARM_BASE}/met_config

# Input/Output directories can be left empty if the corresponding template contains the full path to the files
ASCII2NC_INPUT_DIR = 
ASCII2NC_OUTPUT_DIR =

# End of [dir] section and start of [filename_templates] section
[filename_templates]

# Template to look for input to ASCII2NC relative to ASCII2NC_INPUT_DIR
ASCII2NC_INPUT_TEMPLATE = "{MET_INSTALL_DIR}/share/met/python/read_ascii_point.py {INPUT_BASE}/met_test/data/sample_obs/ascii/sample_ascii_obs.txt"

# Template to use to write output from ASCII2NC
ASCII2NC_OUTPUT_TEMPLATE = {OUTPUT_BASE}/met_tool_wrapper/ASCII2NC/ascii2nc_python_user.nc

[user_env_vars]
MET_PYTHON_EXE = python3

MET Configuration

None. No MET configuration file for ASCII2NC is used in this case.

Python Embedding

This use case calls a Python script to read the input data. The Python script is stored in the MET repository: /path/to/MET/installation/share/met/python/read_ascii_point.py

read_ascii_point.py

Running METplus

This use case can be run two ways:

1. Passing in ASCII2NC_python_embedding_user_py.conf then a user-specific system configuration file:

   run_metplus.py -c /path/to/METplus/parm/use_cases/met_tool_wrapper/ASCII2NC/ASCII2NC_python_embedding_user_py.conf -c /path/to/user_system.conf
   

2. Modifying the configurations in parm/metplus_config, then passing in ASCII2NC_python_embedding_user_py.conf:

   run_metplus.py -c /path/to/METplus/parm/use_cases/met_tool_wrapper/ASCII2NC/ASCII2NC_python_embedding_user_py.conf
   

The former method is recommended. Whether you add them to a user-specific configuration file or modify the metplus_config files, the following variables must be set correctly:

• INPUT_BASE - Path to directory where sample data tarballs are unpacked (See Datasets section to obtain tarballs). This is not required to run METplus, but it is required to run the examples in parm/use_cases

• OUTPUT_BASE - Path where METplus output will be written. This must be in a location where you have write permissions

• MET_INSTALL_DIR - Path to location where MET is installed locally

Example User Configuration File:

[dir]
INPUT_BASE = /path/to/sample/input/data
OUTPUT_BASE = /path/to/output/dir
MET_INSTALL_DIR = /path/to/met-X.Y

NOTE: All of these items must be found under the [dir] section.

Expected Output

A successful run will output the following both to the screen and to the logfile:

INFO: METplus has successfully finished running.

Refer to the value set for OUTPUT_BASE to find where the output data was generated. Output for this use case will be found in met_tool_wrapper/ASCII2NC (relative to OUTPUT_BASE) and will contain the following file:

• ascii2nc_python_user.nc

Keywords

sphinx_gallery_thumbnail_path = ‘_static/met_tool_wrapper-ASCII2NC.png’

Note

ASCII2NCToolUseCase, PythonEmbeddingFileUseCase, MET_PYTHON_EXEUseCase